<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script src="lib/react/react.development.js"></script>
    <script src="lib/react/react-dom.development.js"></script>
    <script src="lib/babel.min.js"></script>
  </head>
  <body>
    <div id="root"></div>
    <script type="text/babel">
      class HelloWorld extends React.Component {
        constructor(props) {
          super();
          this.state = {
            arr: [1, 2, 3, 4],
          };
        }
        render() {
          return (
            <ul>
              {this.state.arr.map((item) => (
                <li key={item}>li_{item}</li>
              ))}
            </ul>
          );
        }
      }

      ReactDOM.render(<HelloWorld />, document.getElementById("root"));
    </script>
  </body>
</html>
